Screen.



H. K. BURCH.

SCREEN. APPLICATION FILED MAR. 13. I916.

1,224,598. Patented May1, 1917.

2 SHEETS-SHEET I- WITNESS INVENTOR H. K. BURCH.

SCREEN.

APPLICATION FILED MAR. 13. I916- Patented May 1, 1917.

2 SHEETS-SHEET 2 m: mzRRls Pzrsns 0.. WASNINGTON. o c.

FFIQ.

HENRY KENYON BURCH, OF MIAMI, ARIZONA.

SCREEN.

Specification of Letters Patent.

Patented May 1, 1917.

Application filed March 13, 1916. Serial No. 83,856.

To all whom it may concern.

Be it known that I, HENRY KENYON BURCH, residing at Miami, in the county of Gila and State of Arizona, a citizen ofthe United States, have invented or discovered certain new and useful Improvements in Screens, of which improvements the following is a specification.

The invention described herein, relates to certain improvements in screening diaphragms for ball mills. It has heretofore been the practice to form these diaphragms, which are arranged within a drum closely adjacent to one end of the latter, of a series of V shaped sections or sectors, each sector, consisting of a frame having radial side pieces and of transverse bars, entendmg from side piece to side piece, and mdependently removable from the frame. This construction involves considerable labor, not only in the original manufacture, but also for repairs. Portionsof the frames require planing, and also the spaced bars which form the screen. The object of the invention herein described, is to provide a screening diaphragm, or grate, consisting of a bar of suitable cross section, spirally wound, each spiral being suitably spaced from the adjacent spirals. The invention 1s heremafter more fully described and claimed.

In the accompanying drawings forming a part of this specification, Figure l is a sectional elevation of a portion of a ball mlll, showing my improved screen in position therein; Fig. 2 is a sectional view on a plane indicated by the line III-III, Fig. 1; Fig. 3 is a similar view but illustrates a modification in the method of securing the grating or screen in position in a ball mill; Fig. 4 is a detail view showing side and edge portions of the strip of which the screen or grating is made; Fig. 5 is a side View of a portion of the screen shown in Fig. 3; Fig. 6 is a sectional view of the construction shown in Fig. 5; Fig. 7 shows sectional views on planes at right angles to each other, illustrating a modification in the method of securing the screen in position in a ball mill, and Fig. 8 is a similar view, illustrating a further modification.

In lieu of forming the screening grate or diaphragm 5 of a ball mill, of a series of sections, it is in the practice of my invention, formed of a continuous flat strip of metal, of suitable cross-sectional dimensions. This strip, after being formed as it may be in a rolling mill, is wound spirally, as is clearly shown in Fig. 1. lVhere the size of the drum of the ball mill renders it impracticable to produce a strip of suficient length to form the entire screen, two or more strips may be connected end to end by welding or clamping or in suitable way.

In order to insure the suitable spacing of adjacent spirals, small projections 6 are formed preferably in the rolling operation on one side thereof, as clearly shown in Fig. 4. The spacing apartof these projections on the strip, will depend a great deal on the gage of the strip, but they should be at all times sufficiently close so as to insure a uniform spacing at all parts of the screen. In winding the bar into spiral form, the bar is placed under considerable strain, and means should be employed to prevent an unwinding of the spirals. This may be effected in a variety of ways, as for example dovetailed notches may be formed in the edge of the spiral on one side of the screen for the reception of correspondingly shaped bars 7, as shown in Fig. 8, or holes may be formed through the spirals for the reception of rods 8 as shown in Fig. 7. The dovetailed bar or the rod 8 may be secured in position by any suitable means, as for example, by welding their respective ends to the inner and outer spirals of the screen.

The screen thus formed, may be secured in position on the drum in any suitable manner. In the construction shown in Figs. 1 and 2, the innermost spiral of the screen rests upon shoulder 9 formed in the periphery of the center plate 10 of the mill, while the outer periphery of the screen or diaphragm is engaged by bolts passing through the shell of the drum. It will be understood that in the operation of the mill, the screen will be subjected to pressure of the contained material and the balls, tending to force it toward the discharge end of the drum, and that such pressure will be greatest adjacent to the periphery of the screen. Hence it is preferred to provide a lateral support for the screen, in the form of an inwardly projecting flange 11. If desired, the intermediate portions of the screen may be supported laterally by radial ribs 12 formed on the head 13 at the discharge end of the drum.

If preferred, the screen may be held in position by means of bolts 14 havin their heads countersunk in the screen whi e their stems pass through the ribs 12 and head 13, as shown in Figs. 3, 5 and 6.

In some cases, it is desirable that the spaces between the spirals should be flared so as to minimize the liability of their being clogged. This result can be attained in the improved screen, by rolling one edge of the strip somewhat thicker than the opposite edge as indicated in Fig. 8.

It will be observed that practically no machining of my improved screen is necessary, the only work necessary, after the rolling of the strip, being to wind the latter on a suitable form, and then either form notches for the dove-tail bar or holes for the rod, and the welding of the latter as before described, and the welding of the ends of the locking bar or rod, as hereinbefore described.

Itis characteristic of the screen shown herein that it is an integral structure made wholly of a continuous strip of metal, hav-- ing spaced projections integral therewith and wound to form a spiral. It is also characteristic of the screen that in the winding operation the projections on one spiral are caused to bear on an adjacent spiral. This construction in which one spiral bears on the other, insures the holding of the spirals Copies of this patent may be obtained for While I have shown and described my improved screen in connection with a ball mill,

it will be understood that the screen construction, as described, can be employed for other purposes and in fact for any purpose for which screens are usually employed.

I claim herein as my invention:

1. A screen, consisting of a bar or rod having suitably spaced projections on one side, and wound to form a substantially fiat spiral,

2. A screen having in combination a bar or rod having suitably spaced projections made on one'side thereof and so wound that the projections on one spiral bear against the plain side of an adjacent spiral,'and means for locking the spirals, one with the other.

In testimony whereof, I have hereunto set my hand.

HENRY KENYON BURCH. Witnesses:

CHARLES L. RAWLINS, PETER O. LITTLE.

five cents each, by addressing the Commissioner of Patents,

Washington, D. G. 

